Polyphenylene ethers (PPE) as well as blends prepared therefrom constitute an invaluable class of engineering thermoplastic resins. Resins of polyphenylene ethers are characterized by a unique combination of chemical, physical and electrical properties. For instance, they have favorable heat deflection temperatures and generally display high impact strengths. As a result of this unique combination of properties, resins of polyphenylene ethers are suitable for a broad range of commercial applications.
Typically, polyphenylene ethers are prepared via the oxidative coupling of phenols in the presence of a catalyst, and the oxidative coupling is carried out in an organic solvent such as toluene. Such phenols are conventionally 2,6-dimethylphenols and not 2,6-disubstituted-4-alkylphenols (common by-products of 2,6-dimethylphenol synthesis) which are typically disposed of since they characteristically decrease polymerization rates and act as polymer chain terminators.
Subsequent to polymerizing the phenols, solid polymer is isolated by precipitation with non-solvents like methanol. However, the typical oxidative coupling method is not very favorable, since among other reasons, it requires the use of large quantities of environmentally unfriendly solvents which must be recovered and purified by expensive and time consuming process steps.
It is of increasing interest to prepare polyarylene ethers by a method which does not, for instance, require the use of organic solvents. Moreover, it is of increasing interest to prepare such ethers by a method which employs 2,6-disubstituted-4-alkylphenols since they are available and their disposal may be difficult, time consuming and costly.